Disk cartridge having chamfered wall portion

ABSTRACT

A disk cartridge with a case comprises upper and lower shell halves, each of which has a head insertion hole and a spindle insertion hole. A pair of projections are provided inwardly at a joint portion between the two holes. The peripheral wall portions of the spindle insertion hole are extended inwardly toward tips of the projections in an arched form. An almost annular projection is provided along a periphery of the spindle insertion hole to increase a supporting portion for supporting the disk when the spindle is taken off from the spindle insertion hole. The inner peripheral walls of the head insertion hole are chamfered. A corner of the groove is chamfered to prevent the corner of the groove from being caught by a part of the guide frame.

This is a continuation of application Ser. No. 08/234,701 filed on Apr.28, 1994, now abandoned, which is a continuation of application Ser. No.07/931,849 filed on Aug. 18, 1992, now abandoned, which is a divisionalof application Ser. No. 07/647,571 filed on Jan. 28, 1991 now U.S. Pat.No. 5,166,922.

BACKGROUND OF THE INVENTION

The present invention relates to a disk cartridge for encasing arecording medium such as an optical disk or a magnetic disk.

In general, a magnetic disk or an optical disk is encased in a cassettecase made of two shell halves. A hole into which a spindle for rotatingthe disk is to be inserted is formed in the center portion of thecassette case. Adjacent to the spindle hole, a head insertion hole intowhich a writing/reading head is to be inserted is formed in the radialdirection to traverse the recording surface of the disk. The headinsertion hole is opened and closed by a shutter slidingly provided onthe cassette case.

The front end of the cassette case has a guide portion along which isreciprocatingly moved a slider to hold the shutter for opening andclosing the head insertion hole and the spindle insertion hole. Theslider is in a rectangular bar-shape and holds the bent portion of theshutter. The shutter has a pair of side plate portions extendingparallel to each other from the opposite sides of the bent portionthereof in order to open and close the above two holes of the cassettecase.

There is provided a twist coil spring between the front portion of theslider and the cassette case for urging the shutter in the directionwhere the two holes are closed.

As mentioned above, the opposite ends of the twist coil spring are heldat the front end of the slider and at the front corner of the cassettecase, respectively. However, if the disk cartridge is subjected to animpact force, e.g., when it is dropped on a floor, the twist coil springmay be disconnected from the front end of the slider and the corner ofthe cassette case. Further, an operation for connecting the coil springto the slider and the cassette case is troublesome, and dust may enterthe cassette case when the case is dropped to move the shutter to openthe two holes of the cassette case.

A reading/writing device (player) for receiving the disk cartridge has apair of drive pins for opening and closing the shutter, and, however,neither a relational movement between the drive pins and the shutter nora charging movement of the disk cartridge into the reading/writingdevice is smooth.

The disk is held, at its center portion, by the spindle in a floatingcondition in the cassette case, and, however, the disk cannot be heldstably therein. Moreover, when the disk is rotationally held, theinformation recording surface of the disk sometimes abuts against theinner surface of the case to cause a scratch and a damage thereonto.When the disk happens to strongly abut against the edge of the headinsertion hole, the information recording surface of the disk may suffera damage. When the peripheral edge of the disk in the case strikesagainst the corner of a substantially circular surrounding wall, theperipheral edge thereof may suffer a damage.

In addition, there is provided a writing protection mechanism in thecase for preventing old information having been already recorded on thedisk from being erased by recording new information onto the disk.However, there may occur a case that some parts of the writingprotection mechanism are assembled upside down in the case.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a disk cartridge in which aspring for urging a shutter does not easily come off from the shutterand a corner of a case and can be easily assembled in the case.

It is another object of this invention to provide a disk cartridge inwhich a drive pin of a reading/writing device can open and close thedisk cartridge smoothly.

It is still another object to provide a disk cartridge which can holdstably a disk therein without generating a scratch or damage on thedisk.

It is still another object to provide a disk cartridge which has awriting protection mechanism capable of being easily assembled.

According to one aspect of this invention, there is provided a diskcartridge with a shutter which is slidably mounted on a case and urgedby an elastic spring in a direction where an opening portion formed inthe case is closed in order to open and close the opening portionthereof, wherein the shutter is mounted onto the case through a sliderwhich is slidably accommodated at front portion of the case, the sliderhaving one end with an insertion hole for receiving a bent end providedat an end of an arm of the elastic spring, the insertion hole being bentto form a hook hole in a hook-shape in longitudinal direction of theslider and provided, at an inlet thereof with a sharp projectionextending inwardly thereof for holding the bent end of the elasticspring and a cut away path communicated with the bent hole and extendedin longitudinal direction of the slider to guide the arm of the spring,the inlet of the insertion hole having a width for permitting the bentend to pass therethrough.

According to another aspect of this invention, there is provided a diskcartridge with a shutter which is slidably mounted on a case and urgedby an elastic spring in a direction where an opening portion formed inthe case is closed in order to open and close the opening portionthereof, wherein the shutter is mounted onto the case through a sliderwhich is slidably accommodated at front portion of the case, the sliderhaving one end with an insertion hole for receiving a bent end providedat an end of an arm of the elastic spring, the insertion hole having aclosed space for holding therein the bent end thereof extending inwidthwise direction of the slider and a cut away path extended inlongitudinal direction of the slider to be communicated with the closedspace to guide the arm of the spring.

According to still another aspect of this invention, there is provided adisk cartridge with a shutter which is slidably mounted on a case andurged by an elastic spring in a direction where an opening portionformed in the case is closed in order to open and close the openingportion thereof, wherein a bent end is formed at an end of an arm of theelastic spring, a pair of hook members being provided near or at a partof peripheral side wall of the case so as to be extended parallel toeach other in a direction where the elastic spring is expanded andshrunken, a pair of hooks being provided at distal ends thereof,respectively, to form an insertion inlet for the bent end thereof whichis held in a space defined by the hook members.

According to still another aspect of this invention, there is provided adisk cartridge with a shutter which is reciprocatingly provided on acase through a slider in order to open and close an opening portion ofthe case, wherein a curved surface is provided at a corner of a rear endof the slider in a direction where the shutter opens the opening portionof the case, a Fear end of the shutter, corresponding to the rear end ofthe slider being cut away to form a cut portion from which the curvedsurface is projected outwardly.

According to still another aspect of this invention, there is provided adisk cartridge with a shutter connected to a slider movable on a guideportion provided on front side of a case for opening and closing anopening portion of the case, the slider having a receiving recess forreceiving a drive pin provided in a reading/writing device to move theshutter through the slider, wherein the case has a shutter lockingmechanism for locking the shutter at its closing position.

According to still another aspect of this invention, there is provided adisk cartridge having an upper and a lower shell halves assembledtogether with each other to form a case to hold a disk therebetween, thecase having a spindle insertion hole at its center position, into whicha spindle for rotating the disk with a hub while holding the hub of thedisk is inserted, the spindle insertion hole being opened and closed bya movable shutter, wherein a projection is formed, on an inner wall ofthe case, at a position separated from a peripheral edge of the spindlehole and opposed to a non-recording surface of the disk so as tosurround the spindle hole.

According to still another aspect of this invention, there is provided adisk cartridge with a case having a spindle insertion hole, at itscenter portion, for receiving a spindle for rotating a disk accommodatedin the case, wherein a projection is formed, on an inner wall of thecase, along a peripheral edge of the spindle insertion hole or at aposition near the spindle insertion hole so as to be opposed to anon-recording surface of the disk, the projection being covered with anouter layer having at least one of slippery and elastic properties.

According to still another aspect of this invention, there is provided adisk cartridge with a case having a spindle insertion hole, at itscenter portion, for receiving a spindle for rotating a disk accommodatedin the case, wherein a film having a slippery property such as PET isattached onto an inner wall of the case along a peripheral edge of thespindle insertion hole or at a position near the spindle insertion hole.

According to still another aspect of this invention, there is provided adisk cartridge with a case comprising an upper and a lower shell halves,each of which has a circular surrounding wall on its inner wall foraccommodating a disk, wherein a joint portion between a side peripheralwall and the surrounding wall is curved or chamfered.

According to still another aspect of this invention, there is provided adisk cartridge with a groove on each side of a peripheral wall of a casefor receiving a drawing arm provided in a guide frame of areading/writing device to draw the case thereinto, wherein a corner ofthe groove is chamfered to prevent the corner of the groove from beingcaught by a part of the guide frame.

According to still another aspect of this invention, there is provided adisk cartridge with a case comprising an upper and a lower shell halffor accommodating a disk therein and a writing protection mechanism forpreventing new information from being recorded again onto a recordedsurface of the disk onto which old information has been alreadyrecorded, wherein the mechanism comprises: a movable plug having ablock-like main body held movably in the case and at least one legextended from an end of an end face of the plug in a direction where theplug is moved; a guide part provided in the case for holdingreciprocatingly the main body of the plug therein; a projection providedon an inner surface of the guide part for selectively holding themovable plug at two positions while cooperating with the leg of theplug; an opening means which is provided in the guide part so as to beclosed and opened when the plug is located at one position and atanother position, respectively; and a raised portion provided on a flatwall with which the other end face with no leg of the plug is engagedwhen the plug is property assembled in the guide part.

According to still another aspect of this invention, there is provided adisk cartridge with a case comprising an upper and a lower shell halvesfor accommodating a disk and an opening portion provided, on each shellhalf, so as to be opened and closed by a shutter, wherein each shellhalf is formed by an injection molding in which a mold having a singleinjection hole is used, the injection hole being formed in the mold, ata position corresponding to a part on the case which is covered with acertain member of the disk cartridge.

Further objects, features and other aspects of this invention will beunderstood from the following detailed description of the preferredembodiments of this invention with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a perspective view of a disk cartridge according to thisinvention;

FIG. 2 is a partial perspective view of the disk cartridge when ashutter is opened;

FIG. 3 is an exploded perspective view of the shutter and a slider;

FIG. 4 is a perspective view of a guide portion of the disk cartridge;

FIGS. 5 and 6 are two operational views showing a function of a twistcoil spring when the shutter is opened and closed;

FIG. 7 is a longitudinally sectional view of a front portion of theslider;

FIG. 8 is a cross sectional view taken along the line VIII--VIII;

FIG. 9 is a front view of the slider;

FIG. 10 is a perspective view of the front portion of the slider;

FIG. 11 is a longitudinally sectional view of a front portion of aslider, showing another embodiment with respect to a connecting portionof the slider and the twist coil spring;

FIG. 12 is a cross sectional view taken along the line XII--XII;

FIG. 13 is a perspective view of the slider shown in FIG. 11;

FIG. 14 is a front view of the slider shown in FIG. 11;

FIG. 15 is a perspective view of a connecting portion of the twist coilspring and a lower shell half of the disk cartridge;

FIG. 16 is an explanatory view showing a function of the connectingportion shown in FIG. 15;

FIG. 17 is a perspective view of the twist coil spring;

FIGS. 18 and 19 are two explanatory views showing a function of theconnecting portion shown in FIG. 15 when the shutter is opened andclosed;

FIGS. 20 and 21 are two explanatory views showing a state of engagementof a drive pin and the slider, respectively;

FIG. 22 is a longitudinally sectional view of a front part of the diskcartridge, showing a shutter locking mechanism;

FIG. 23 is an exploded perspective view showing a state of engagement ofthe slider and a stopper for the shutter locking mechanism;

FIG. 24 is a plan view of a rear portion of the slider;

FIG. 25 is a side view of the rear portion of the slider;

FIG. 26 is a cross sectional view taken along the line XXVI--XXVI;

FIG. 27 is a longitudinally sectional view taken along the lineXXVII--XXVII;

FIG. 28 is a plan view of the stopper for the shutter locking mechanism;

FIG. 29 is a side view of the stopper;

FIG. 30 is a cross sectional view taken along the line XXX--XXX;

FIG. 31 is a bottom view of the stopper;

FIG. 32 is a cross sectional view of a center portion of the diskcartridge;

FIG. 33 is a perspective view of an inner side of an upper shell half;

FIG. 34 is a perspective view of an inner side of a lower shell half;

FIG. 35 is a plan view of a center portion of either the upper or lowershell half;

FIG. 36 is a cross sectional view of a center portion of the diskcartridge, showing other embodiment;

FIG. 37 is a cross sectional view of a center portion of the diskcartridge, showing still other embodiment;

FIG. 38 is a cross sectional view of a center portion of the diskcartridge, showing still other embodiment;

FIG. 39 is a cross sectional view of an annular projection provided onthe center portion of each of the upper and lower shell halves;

FIG. 40 is a cross sectional view taken along the line XXXX--XXXX;

FIGS. 41 and 42 are two perspective views of the upper and lower shellhalves, showing other embodiment of a surrounding wall for receiving adisk, respectively;

FIG. 43 is an enlarged plan view of a joint part between the surroundingwall and a side wall of the lower shell half;

FIG. 44 is a perspective view of the disk cartridge and a guide frame ofa reading/writing device when the disk cartridge is charged into theguide frame thereof;

FIG. 45 is a partially longitudinal view of a front portion of the sidewall of the disk cartridge;

FIG. 46 is a perspective view of the disk cartridge having a writingprotection mechanism;

FIGS. 47(a) and (b) are two perspective views of a movable plug asviewed in two directions opposite to each other, respectively;

FIGS. 48(a) and (b) ape two plan views of two guide portions fop theleft and right plugs on the left and right sides of the lower shellhalf, respectively;

FIG. 49 is a perspective view of the inner side of the upper shell halfhaving two guide portions for the two protection plugs;

FIG. 50 is a perspective view of the inner side of the lower shell halfhaving two guide portions for the two protection plugs;

FIGS. 51 to 54 are four explanatory views showing a function of thewriting protection mechanism, respectively;

FIG. 55 and 56 are two plan views of two half molds assembled oppositeto each other for forming the upper shell half, respectively; and

FIG. 57 is a perspective view of the disk cartridge having a trace of aninjection hole of an injection mold.

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

As shown in FIGS. 1 and 2, a disk cartridge C for encasing an opticaldisk, has an upper and a lower shell halves 6, 7 which are assembled inalignment with each other to form a case. The center portion of the casehas a spindle insertion hole 8 and a head insertion hole 9 disposedadjacent to the spindle insertion hole 8 to receive a reading/writinghead (not shown) to form an opening portion of the case.

In order to open and close the opening portion, a shutter 10 is providedslidably in the left and right directions on the disk cartridge C. Theshutter 10 is, as shown in FIG. 3, so formed that a stainless plate isbent at its center (top plate 12) to form two closing plates 11, 11opposite to each other. Each closing plate has a slide plate 13 at itslower end. The slide plate 13 is slidably guided by a retaining plate 30attached to the surface of each shell half. The top plate 12 is held byan elongated slider 14 through two screws 15, 15 each of which is passedthrough an opening 16 to be inserted into a receiving hole 17 providedin the slider 14.

The rear portion of the top plate 12 (right portion as viewed in FIG. 3)has an opening 18 in registration with a receiving recess 19 provided atthe rear portion of the slider when the slider 14 and the top plate 12are combined together. The recess 19 receives a drive pin P1 (FIG. 4)provided in a reading/writing device (player) (not shown) to open andclose the shutter 10 when the disk cartridge C is charged into theplayer. Each receiving hole 17 of the slider 14 is opposed to an openingof the top plate 12.

On the opposite side faces of the slider 14 are provided a pair of guidegrooves 20, 20 which engage with two guide rails 21, 21 in a guideportion formed on the front end of the disk cartridge on the side of theplayer. The slider 14 has a slanted surface 22 at its front end, asshown in FIG. 4, so that a drive pin P2 disposed opposite to the drivepin P1 can slide smoothly on the front portion of the slider 14. Thatis, when the disk cartridge C is charged into the player, one of thedrive pins P1, P2 (pin P1 in FIG. 4) is received in the receiving recess19 of the slider 14 through the opening 18 of the top plate 12. Then,the pin P1 is moved in the left direction as viewed in FIG. 4 to openthe spindle insertion hole 8 and the head insertion hole 9. At thattime, the other drive pin P2 rides on the slanted surface 22 to be movedin the right direction. As a result, the two pins P1, P2 are moved inthe opposite directions, and passed by each other.

Thus, the slanted surface 22 of the slider 14 permits the pin P2 toslide smoothly on the slider 14. In this case, the pin P2 which does notfunction to open and close the opening portion of the case is called auseless pin. In contrast, when the disk cartridge C is turned over to becharged into the player, the pin P2 functions to open and close theopening portion thereof while the pin P1 is called a useless pin.

As shown in FIGS. 1, 5 and 6, on the right side of the front end of thedisk cartridge is accommodated a twist coil spring 23 which is providedbetween the front corner of the disk cartridge C and the front portionof the slider 14 to urge the shutter 10 toward the direction where theopening portion of the disk cartridge is closed. The front end of theslider 14 is in the form of a pent roof and has a recess 24 at its lowerside as shown in FIGS. 7 and 10. At the base portion of the front endthereof is provided an insertion hole 25 adjacent to the recess 24 forreceiving a bent end 23a of the coil spring 23. The insertion hole 25has a substantially rectangular shape in its cross section, which canpass the bent end 23a and a substantial V-shape (hook-shape) as a wholein its longitudinal direction to form a hook hole 28b which has aprojecting portion 28 at its turning point. That is, the insertion hole28 has a downslope part slanting downwardly from an inlet 25a at theright end of the recess 24 and an upslope part slanting upwardly fromthe lower end of the downslope part. At the lower position of the inlet25a of the downslope part thereof is provided a sharp projection 26which projects inwardly of the insertion hole 25 to form a space 26a forholding the bent end 23a of the spring 23. There is provided a cut awaypath 27 which extends in the longitudinal direction of the slider 14 tocommunicate with the hook hole 25b. When the bent portion 23a of thecoil spring 23 is inserted into the insertion hole 25, the bent portion23a is passed through the inlet 25a in a state wherein the bent portion23a is extended horizontally in the widthwise direction of the slider 14and wherein an arm 32 of the coil spring 23 is extended vertically to beaccommodated in the path 27.

The bent portion 23a can be thus inserted smoothly deeply into theinsertion hole 25. When the shutter 10 is in a closing state, the bentportion 23a is held in the space 26a by the sharp projection 26projecting in the longitudinal direction of the slider 14. The coilspring 23 is expanded and shrunken, as shown in FIGS. 5 and 6, inresponse to the reciprocal movement of the shutter 10. The bent portion23a of the spring 23 is accommodated deeply in the upslope space of thehook hole 25b when the shutter opens the opening portion of the diskcartridge C in a state wherein the coil spring is shrunken as shown inFIG. 6. In contrast, as mentioned above, the bent portion 23a is held bythe sharp projection 26 in the space 26a as shown in FIG. 7, when theopening portion is closed by the shutter 10. In this manner, the bentportion 23a is reliably held in the insertion hole during the reciprocalmovement of the shutter 10.

In FIGS. 1 and 2, a reference numeral 29 indicates a writing protectionpart for preventing new information from being recorded on the recordingsurface of the disk. As mentioned above, the insertion hole 25 is bentin a V-shape to form the projecting portion 28 at the turning positionof the hook 25b and the sharp projection 26 projecting toward the insideof the insertion hole 25. Therefore, when the bent end of the coilspring 23 is once inserted in the insertion hole 25, it is not easilydisconnected from the insertion hole 25 even if the coil spring 23 ismoved abruptly and an impact force is exerted on the disk cartridge whenit is dropped on a floor. Further, the sharp projection 26 located nearthe inlet 25a of the insertion hole 25 has an upper face to guide thebent end 23a of the coil spring 23 toward inside of the insertion hole25 when the bent end 23a is accommodated in the insertion hole 25.Therefore, an assembling operation of the coil spring 23 and the shutter10 is performed easily and speedily.

Second Embodiment

The connecting portion between the bent end 23a of the coil spring 23and the front end of the slider 14 may be constructed as shown in FIGS.11 to 14. That is, the front end of the slider 14 has a pent roof-shapeprovided with a recess 34 at its lower face, and the base portion of thepent roof-shape is provided with an insertion hole 35 having a closedspace 35c for accommodating the bent end 23a of the coil spring 23. Theinsertion hole 35 is in the shape of a rectangular parallelepiped, andhas, as shown in FIG. 11, a length for receiving the bent end 23athereof in the longitudinal direction of the slider 14. At the front endwalls 35a, 35b in which the closed hole 35C is formed is provided a cutaway path 37 for introduction of the bent end 23 thereof and forswinging motion of the arm 32 thereof during the opening and closingmotion of the shutter 10. The width of the path is determined slightlylarger than that of the arm 32 of the coil spring 23.

When the bent end 23a thereof is accommodated into the insertion hole35, the bent end 23a is extended along the bottom opening of the cutaway path 37 to be inserted into the right end space of insertion hole35 as viewed in FIG. 13, and the bent end 23a is then turned by about 90degrees in the direction indicated by an arrow E.

The coil spring 23 is expanded and shrunken with the bent end 23athereof directed in the widthwise direction of the slider 14. Further,the arm 32 thereof is swung along two opposite walls defining the cutaway path 37. Therefore, the bent end 23a thereof is always held in theinsertion hole 35 so as not to be disconnected therefrom. The bent end23a thereof can be also inserted into the insertion hole 35 in thelongitudinal direction (arrow F) of the slider 14 through the inlet ofthe cut away path 37 in the wall 35a extended vertically as viewed inFIG. 11.

The above structure of the connecting portion between the bent end 23athereof and the front end of the slider 14 permits the bent end 23a tobe reliably held in the insertion hole 35 even if the coil spring ismoved abruptly and the disk cartridge is dropped to be subjected to animpact force.

Third Embodiment

The twist coil spring 23 is, as shown in FIG. 17, made of an elasticwire, and has a center coil portion 31 and two arms 32, 33 extended tothe opposite sides of the center coil portion 31. The ends of the arms32, 33 are bent perpendicularly to those arms 32, 33 to form two bentends 23a, 23b, respectively.

As shown in FIGS. 15 and 16, the lower shell half 7 of the diskcartridge C has, at its front corner, a pair of hook members 535, 536extending parallel to each other in the longitudinal direction of theshell half 7 and formed at the end portions of the guide rails 21, 21.At the respective ends of the hook members 535, 536 are, as shown inFIG. 16, provided a pair of hooks 39, 40 opposed to each other, whichform cooperatively an insertion inlet 38 open in the slanted direction Bwith respect to the widthwise direction A. The two hooks 39, 40 have twosharp projections 39a, 40a projected inwardly in a space 41 defined bythe hook members 535, 536, respectively. The bent end 23b of the coilspring 23 is kept in the space 41.

When the coil spring 23 is expanded and shrunken as shown in FIGS. 18and 19, the bent end 23b thereof is moved between a position 23b₁indicated by a solid line and either a position 23b₂ or a position 23b₃.However, since the insertion inlet 38 is open to the slanted direction Bwith respect to the widthwise direction of the case, the bent end 23b isnever disconnected from the space 41 after it is once accommodatedtherein.

When the disk cartridge C is assembled, the bent end 23b is insertedinto the space 41 in the slanting direction B as shown by a position23b₄ of a dotted line.

The above structure makes it possible to reliably hold the bent end 23bin the space 41, and the bent end 23b can be easily and speedilyinserted when the disk cartridge is assembled.

Fourth Embodiment

A connecting portion between the rear end of the slider 14 and theshutter 10 may be formed as shown in FIGS. 20 and 21. That is, a curvedsurface 42 is formed at the upper corner (the joint portion between thetop face 48 of the slider 14 and the rear end face 41 thereof) of therear end of the slider 14. The rear upper projected end portion of theshutter 10 is cut away obliquely to form a cut portion 43 from which thesmoothly curved surface 42 is projected outwardly. As mentioned above,the slider 14 has, neap its rear end, a receiving hole 44 for receivingeither the drive pin P1 or P2 provided in the player. At the two rearpositions of the guide portion G of the upper and lower shell halves 6,7 are provided two recesses 46, 47 for holding either the pin P1 or P2which is useless. In FIG. 21, the two drive pins P1, P2 correspond tothe upper and lower half shells 6, 7, respectively, and when the diskcartridge C is charged into the player, the drive pin P1 is received inthe receiving hole 44 to open the shutter 10 while the opposite drivepin P2 which is useless is received in the recess 45. Thereafter, when areproduction operation is finished, the drive pin P1 comes off from thereceiving hole 44 to be moved to an original position in a direction D.In synchronism with the movement of the drive pin P1, the useless pin P2comes off from the receiving recess 47 to be moved to an originalposition in a direction C. At this time, the useless pin P2 is movedsmoothly along the curved surface 42 of the slider 14. The diskcartridge C is used for a double-side disk which has a recording surfaceon each side of the disk. Therefore, when the disk cartridge C is turnedover to be charged into the player, the drive pin P2 is inserted intothe receiving hole 44 to open the shutter 10 while the pin P1 isinserted into the receiving recess 47 as a useless pin. The shutter 10is automatically returned by the spring 23 to a closing state.

Fifth Embodiment

The shutter 10 is kept in a closing state by an urged force of the coilspring 23 and, however, the following shutter locking mechanism may be,as shown in FIGS. 22 to 31, provided for safe. That is, the slider 14has, on the bottom side of the rear portion thereof, a cut away portionas shown in FIGS. 25 to 27. The cut away portion 52 extends from therear end of the slider 14 to a portion slightly over the receivingrecess 19 in the longitudinal direction of the slider 14 in a statewherein the left side of the rear portion of the slider 14, as viewed inFIG. 27, is cut away so as to form a stopping hole 53 open to thereceiving recess 19. The stopping hole 53 extends to the upper surfaceof the slider 14 and has a length larger than that of the receivingrecess 19 in the longitudinal direction of the slider 14. Further, thestopping hole 53 has, at its front and rear ends, a slanted ceiling wall54 and a stopping piece 55, respectively. The disk cartridge C has asmall room 56 at a position corresponding to the stopping hole 53 of theslider 14 when the shutter 10 is in a closing state. The room 55comprises, as shown in FIG. 22, two guide walls 57, 57 extended in thelongitudinal direction of the case and a part of the surrounding wall 58surrounding the periphery of the disk. The room 56 has, therein, astopper 59 and an elastic member 150 urging the stopper 59 upwardly.

The stopper 59 comprises, as shown in FIGS. 28 to 31, a plate-like head60, two open legs 61, 61 and a projection 62 extended downwardly betweenthe two open legs 61. The head 60 passes vertically through the stoppinghole 53 and the cut away portion 52 to be projected into the receivingrecess 19 of the slider 14, and has a slanted wall 63 and a stoppingprojection 64 on the front and rear sides on the top face thereof,respectively. The slanted wall 53 contacts the slanted ceiling wall 54of the stopping hole 53 while the stopping projection 64 contacts thestopping piece 55. The elastic member 160 is a compressed coil springwhich is provided between the projection 62 of the stopper 59 and areceiving space 65 at the bottom of the room 56 in order to urge thestopping member 59 toward the slider 14.

Next, the operation of the shutter locking mechanism will be explainedwith reference to the opening and closing movement of the shutter 10.

When the disk cartridge C is located outside of the player, that is, thedisk cartridge C is not used, the shutter 10 is in a closing statewherein the opening portion of the case is closed by the function of thecoil spring 23. At this time, the stopper 59 is, as shown in FIG. 52,pushed upwardly by the elastic member 160 toward the front end of thecase in a state wherein the head 60 of the stopper 59 is accommodated inthe stopping hole 53. Therefore, the slider 14 is fixed at a positionwhere the shutter 10 is in a closing state, so that the shutter 10 iskept at its closing position. Even if an external force is exerted onthe slider 14, the slider 14 is fixed at its closing position by theengagement of the stopping piece 64 of the stopper 59 with the stoppingpiece 55 of the slider 14. The stopper 59 is urged vertically by thespring 160 as viewed in FIG. 22 and, however, a shoulder Sh of thestopper 59 engages with a wall of the case. Therefore, even when theslider 14 is moved in its opening position, the stopper 59 is not pushedout of the room 56 by the spring 160.

When the disk cartridge C is charged into the player, the drive pin P1is inserted into the receiving recess 19 thereby to press downwardly thehead 60 of the stopper 59 against the spring force of the elastic member60, resulting in that the stopper 59 is stopped at the lower portion ofthe cut away portion 52. At this time, the open legs 61, 61 are guidedalong the guide walls 57. With this state, the stopping piece 64 isreleased from the stopping piece 55 to enable the slider 14 to be movedin its opening direction (in the left direction as viewed in FIG. 22).In this manner, in a state wherein the drive pin P1 engages with thereceiving recess 19, the slider 14 can be moved in the opening directionof the shutter 10 so as to be slid along the guide portion G of the caseto open the opening portion of the case. Thereafter, when the drive pinP1 comes off from the receiving recess 19, the slider 14 can be moved inthe closing direction of the shutter 10. The rear end face of the cutaway portion 52 abuts against the slanted wall 63 of the stopper 59shortly before the shutter is completely closed thereby to pressslightly the stopper 59 into the room 56. When the slider 14 is moved toa position where the stopping hole 53 is opposed to the head 60 of thestopper 59, the head 50 is pushed upwardly into the stopping hole 53.Thus, the shutter 10 is again in a locked state. The above lockingstructure can prevent the shutter 10 from opening even when an impactforce is imparted to the disk cartridge C.

Sixth Embodiment

Next, some holding ways of the disk in the disk cartridge will beexplained.

As shown in FIGS. 32 to 35, the disk cartridge C has the upper and lowershell halves 6, 7 as mentioned above. The upper shell half 6 has arectangular flat plate part 74 while the lower shell half 7 has arectangular flat plate part 75. The flat plate part 74 has a peripheralside wall 76 and a substantially circular surrounding wall 78, and theflat plate part 75 has a side peripheral wall 77 and a substantiallycircular surrounding wall 79. The two side walls 76, 77 and the twosurrounding walls 78, 79 are opposed to each other when the upper andlower shell halves are assembled together.

At the center portion of the case comprising the two shell halves isprovided the spindle insertion hole 8 into which a spindle S is insertedto absorb a hub 81 of a disk 80 thereby to rotate the disk 80. The headinsertion hole 9 is provided adjacent to the spindle insertion hole 8.At two positions separated from the respective peripheries of thespindle insertion holes 8, 8 of the both shell halves 6, 7 are providedtwo annular projections each projected toward a non-recording surface ofthe disk 80. When the disk cartridge C is transferred, the disk 80 isstably supported by one of the annular projections 85, 85. In this case,since one of the annular projections 85 contacts the non-recordingsurface thereof, the quality of a recording surface thereof ismaintained.

The upper shell half 6 has, at its corners, a plurality of maleprojections 91, 91 . . . 91 each having a screw hole 92 for receiving afastening screw while the lower shell half 7 has a plurality of femaleprojections 93, 93 . . . 93 formed at the positions corresponding tothose of the male projections 91. Each female projection 93 has a hole94 for receiving one of the male projections 91.

In FIG. 36, a disk 210 accommodated in the disk cartridge C is made ofsynthetic resin such as polycarbonate or the like. On the side of thelower shell half 7 is provided a recording surface 210a outside of anon-recording surface 210b around the spindle insertion hole 8. Theprojections 85, 85 are opposed to the non-recording surface 210. Eachprojection 85 may have an outer layer 100 made of thermoplasticelastomer as an elastic member, which has a slippery property betterthan polycarbonate and is softer than that. The layer 100 and theprojection 85 are formed separately through an injection molding.Further, each projection 85 has an arched shape in cross section on theside of the disk 210. Each outer layer 100 may be formed with nitrilebutadiene rubber (NBR) or ethylene-propylene rubber (EPM) which isformed separately from the projections 85 so as to be engaged therewithor attached thereto by adhesive. In addition, polyacetal having aslippery property may be used as the outer layer 100. The polyacetallayer is formed separately from the projection 85 through injectionmolding. If the disk cartridge C is formed with polyacetal, it canobtain a good wear-resisting property, and, however, cannot obtain agood heat resistance. Accordingly, it is not desirable that the wholepart of the disk cartridge C is made of polyacetal.

In FIG. 36, the projection 85 is formed at a position separately fromthe periphery of the spindle hole 8. However, in consideration of onlyprevention of wear of the disk and elastic support thereof, the outerlayer 100 may be formed on a conventional projection provided at theedge of the spindle insertion hole 8. That is, as shown in FIG. 37,fluoro resin (coating layer) may be attached to the top surface of twoannular projections 101, 101 each formed adjacent to the periphery ofthe spindle insertion hole 8.

Further, FIG. 38 shows two annular projections 110, 110 each having anintermediate layer 111 as an elastic layer made of thermoplasticelastomer with which an annular base projecting portion 112 made ofpolycarbonate is covered, and an outer layer 113 made of fluoro resinhaving a slippery property with which the intermediate layer 111 iscoated. Each projection 110 has an arched shape in cross section. Theintermediate layer 111 is formed separately from the base projectingportion 112.

In general, a hard coating process is performed on the surface of thedisk for protection of the surface while the disk is rotated. However,coating material is not attached onto the center portion of the diskbecause of rotational centrifugal force exerted on the coating material.Therefore, each annular projection mentioned above can prevent anon-coated surface of the disk from contacting the inner surface of thecase of the disk cartridge thereby to avoid wear, damage or scratches onthe disk and the case. When the spindle S is stopped to be retractedfrom the hub of the disk, the disk 210 continues its rotation under itsinertia force. At this time, the non-recording surface 210b contacts theannular projections 85, 101, 110. However, since the projections are notonly covered with the outer layers 100, 102, 113 each having a slipperyproperty, respectively, but also formed in an arched shape in theircross section, a wear between the disk and the projections can beeffectively avoided.

Instead of the above annular projections, an annular film 161 made of aslippery material such as PET may be attached onto the periphery of thespindle insertion hole 8 in order to avoid generation of scratches onthe disk.

Seventh Embodiment

FIG. 40 shows a cross sectional view of the head insertion hole 9 whoseinner edge is formed in an arched shape by a chamfering operation. Inthis manner, if each chsmfered edge is provided at the inner edge of thehead insertion hole 9, generation of scratches or cracks onto thesurface of the disk can be effectively avoided even when the disk abutsagainst the edge.

Eighth Embodiment

As shown in FIGS. 41 to 43, the surrounding walls 78, 79 of the upperand lower shell halves 6, 7 have joint portions 78a, 79a for connectingthem to the side peripheral walls 76, 77, respectively. Each of thejoint portions 78a, 79a have a chamfered, arched or curved shape whichcan eliminate generation of wear, scratches or cracks on the jointportion and the periphery of the disk especially when the disk isdropped or transferred.

The distal end of the joint portions 78a, 79a may be slightly separatedfrom the peripheral side walls 76, respectively.

Ninth Embodiment

In FIG. 44, the both side walls 130, 130 of the disk cartridge C havetwo respective guide grooves 131, 131 with which two drawing arms 162,162 for drawing the cartridge C into a guide frame 133 provided in theplayer are engaged, respectively. Each of the guide recess 131 isextended in the front and rear directions and is located near the frontend of each side wall thereof. Each recess 131 comprises two parts, eachof which is provided in one shell half. At the rear end of each groove131 is, as shown in FIG. 45, provided a chamfered corner having anarched shape to prevent the inner surface of the guide frame 133 fromcatching the corner of each groove 131 thereby to ensure a smoothcharging operation of the cartridge C when the disk cartridge C ischarged into the player.

Tenth Embodiment

The disk cartridge C has a pair of writing protection mechanisms 29a,29b on the right and left sides at the rear part of the cartridge C,respectively. The mechanism 29a is for an upper surface of the diskwhile the mechanism 29b is for a lower surface of the disk. Each of themechanisms 29a, 29b has, as shown in FIG. 47, a movable plug 311. Theplug 311 has a block-like main body and a pair of legs 313, 313 extendedfrom one end surface of the main body in its moving direction thereof.In the two mechanisms, the same plug 311 is used in a state wherein theway of assembling them is reversed to each other. The main body 312 hastwo circular projections 314, 315 on its upper and lower faces. Theprojection 314 has a hole 316 into which a tool is inserted when theplug 311 is moved for protection of writing. The two legs 313, 313 areextended parallel to each other and have two stopping pieces 317, 317directed outwardly at their distal ends, respectively.

The writing protection mechanisms 29a, 29b have, in FIG. 48, two dividedguide parts 318b, 319a for holding movably the plugs 311 on the lowershell half 7 and, in FIG. 49, two divided guide parts 319b, 318a. Theseguide parts are joined together to form a pair of guide parts 500, 501(FIG. 46) in which the plugs 311 are movably held. That is, the dividedguide parts 318a, 319b of the upper shell half 6 are joined togetherwith the divided guide parts 318a, 319b, respectively, to form tworooms, one of which is composed of a pair of flat walls 320a, 320b and apair of upright walls 322a, 322b, the other of which is composed of apair of flat walls 321a, 321b and a pair of upright walls 323a, 323b.

The upright walls 322a, 322b for one room and the upright walls 323a,323b for the other room are opposed to each other, respectively.

The upright wall 322a of the upper shell half has, at its inner surface,two projections 327, 327 for cooperating with the plug 311 for themechanism 29b while the upright wall 323a of the lower shell half has,at its inner surface, two projections 327, 327 for cooperating with theplug 311 for the mechanism 29a. Each projection 327 has a predeterminedwidth, and its left and right ends are engaged with the stoppingprojection 317 of the leg 313. That is, each plug 311 can take twopositions, i.e., a non-operating position which is indicated by a solidline and an operating position which is indicated by a dotted line inFIG. 48(b). The plug 311 is selectively fixed at the two positions bythe function of the two projections 317, 327 cooperating with the legs317 of the plug 311.

The flat walls 320a, 320b, 321a, 321b have four elongated openings 324a,324b, 325a, 325b. A pair of the openings 324a, 324b of the flat walls320a, 320b and a pair of the openings 325a, 425b of the flat walls 321a,321b are opposed to each other, respectively, when the upper and lowershell halves 6, 7 are assembled. The two elongated openings in each pairare communicated with each other and closed to each other in response tothe movement of the plugs 311. The flat wall 320b of the lower shellhalf 7 for the writing protection mechanism 29b and the flat wall 321bof the upper shell half 6 for the writing protection mechanism 29a areprovided with two raised portions 326, 326, respectively. In the casethat each plug 311 is properly assembled in each of the mechanisms 29a,29b, the surfaces of the main body of the plug 311, which have no legs313 contact the flat walls 320b, 321b, respectively, and each raisedportion 326 is provided on each flat wall at a position where it doesnot obstruct the left and right movement of each plug 311.

The assembly of the writing protection mechanisms will now be explained.

Before the assembly of the upper and lower shell halves 6, 7, the twoplugs 311, 311 are, as shown in FIG. 51, inserted into the respectiveleft and right divided guide parts 318b, 319a.

At this time, the left movable plug 311 stands upright as shown in FIG.51, with the projection 315 being accommodated in the opening 324b, andwith the legs 313 being located over the raised portion 326. Incontrast, the right movable plug 311 stands upright with the projection314 opposite to the projection 311 being accommodated in the opening325a and with the legs 313 being accommodated in the guiding portion319a.

At the same time, the disk is accommodated in the case. Thereafter, theupper shell half 6 is, as shown in FIG. 52, assembled onto the lowershell half 7 in such a manner that the female projections 93 of thelower shell half 7 receive the male projections 91 of the lower shellhalf 6, respectively (FIGS. 33 and 34). At this time, the projection 314of the left plug 311 is received in the opening 324a of the upper shellhalf 6 with the legs 313 contacting the flat wall 320a while theprojection 315 of the right plug 311 is received in the opening 325bwith the legs 313 contacting the flat wall 321a. Thus, the writingprotection mechanisms 29a, 29b are assembled.

However, there is a case that the plug 311 may be inserted upside downin the guided portion 500 or 501. At that time, the legs 313 ride on theraised portion 326 of the flat wall 320b or 321b, resulting in that theplug 311 stands obliquely. If the upper shell half 6 is put on the plug311 obliquely, the side wall 76 of the upper shell half66 is floatedfrom the side wall 77 of the lower shell half 77 to generate a clearanceC between the two side walls 76, 77. In this manner, a worker or anoperator can detect the insertion miss of the plug 311 thereby tocorrect the posture of the plug 311.

When the two writing protection mechanisms 29a, 29b are correctlyassembled, the protection mechanism 29a functions to protect writing ofinformation onto the front surface of the disk while the mechanism 29bfunctions to protect it onto the back surface thereof (FIG. 46 is aperspective view of the case as viewed from the back side thereof). Theplug 311 of the mechanism 29a is held in a state wherein the projection314 having the insertion hole 316 is directed downwardly while the plug311 of the mechanism 29b is held in a state wherein the projection 314having the insertion hole 316 is directed upwardly (FIG. 46).

When the mechanism 29b for the back surface of the disk is operated, apin is inserted into the hole 316 of the projection 314 of the plug 311to move the plug 311 in the left direction, as viewed in FIG. 46, whilethe engaging projections 317 of the legs 313 ride over the engagingprojections 327.

As a result, a part of the opening 325a of the upper shell half 6 iscommunicated with a part of the opening 325b to form a through hole intowhich a detection pin b provided in the player is inserted to protectits writing. The operation of the opposite mechanism 29a for the frontsurface of the disk surface of the disk is performed in the same manner.

In this embodiment, the disk cartridge C is fop a double-side disk.However, one writing protection mechanism is used in the case of aone-side disk.

The above structure of the mechanisms 29a, 29b makes it possible toeasily find out the incorrect insertion of the plug by mistake.

Eleventh Embodiment

A mold for forming the disk cartridge will now be explained.

Two molds are prepared for the upper and lower shell halves 6, 7.

First, the mold for the upper shell half 6 will be explained. The moldcomprises, as shown in FIG. 55, a half mold 413 shown in FIG. 55 and ahalf mold 414 shown in FIG. 56. The half mold 413 has a cavity with ashape corresponding to an outer shape of the upper shell half 6 whilethe half mold 414 has a cavity 416 with a shape corresponding to anouter shape of the inner shape of the upper shell half 6. When the twocavities are combined together to form a single cavity for forming theupper shell half 6.

The half mold 413 is provided with a single gate 417 (injection hole),at a position deviated from the center of the cavity 415. The positioncorresponds to a position 415a where the retaining plate 30 is attachedto the surface of the case in order to guide the slide plate 13 of theshutter 10. The cavity 415 is provided with a flat forming part 415c anda guide groove forming part 415 in addition to the retaining plateattaching groove 415a. The half mold 414 comprises a plurality offorming parts 416a, 416a . . . 416a located at four corners of thecavity 416 and surrounding wall forming part 416b for forming thesurrounding wall 78.

When the upper shell half 6 is formed by the two half molds 413, 414,they are combined to form the cavity corresponding to the upper shellhalf 6, into which a melted synthetic resin such as polycarbonate or thelike is injected through the injection hole 417.

In the case of a 5-inch disk cartridge, the diameter of the injectionhole 417 is determined at 1.5 mm. The injection conditions are asfollows.

Mold temperature: 80° to 90° C.

Injection pressure: 1500 to 1600 kg/cm²

Melted resin temperature: 250° to 280° C.

The mold for the lower shell half 7 has a similar construction.

After an injection forming is performed, a gate trace 423 is coveredwith the retaining plate 30 on each shell half. Further, if each shellhalf is formed by the mold having a single injection hole 417 in thismanner, there is no weld pattern on the surface of the case, which is awave-form pattern formed at a position where melt resins flown into thecavity from different injection holes are joined. Therefore, a goodouter appearance is obtained.

In each embodiment, various disk cartridges for accommodating a diskhaving a diameter of 5 inches are explained, and, however, thisinvention can be adapted to other disk cartridges, e.g., a diskcartridge for a 3.5-inch disk.

What is claimed is:
 1. A disk cartridge with a case comprising upper andlower shell halves assembled with each other to hold a disktherebetween, the case having a head insertion hole for receiving areading/writing head adjacent a spindle insertion hole at center of thecase for receiving a spindle for rotating the disk, a groove on eachside of a peripheral wall of the case for receiving a drawing armprovided in a guide frame of a reading/writing device to draw the casethereinto and a pair of projections provided inwardly at a joint portionbetween the head insertion hole and the spindle insertion hole, theimprovement in which each projection at the joint portion between thehead and spindle insertion holes has a triangular shape comprising astraight portion projected inwardly and almost perpendicularly to anedge portion of the head insertion hole and an arched portion formingpart of an edge of the spindle insertion hole, an almost annularprojection is provided along a periphery of the spindle insertion hole,the projection being opposed to a non-recording surface of the disk andbeing chamfered to form an arched shape in cross-section, and innerperipheral walls of the head insertion hole are chamfered, a corner ofthe groove being chamfered to prevent the corner of the groove frombeing caught by a part of the guide frame.
 2. A disk cartridge accordingto claim 1, wherein each half shell has a circular surrounding wall onits inner wall for accommodating the disk, a joint portion between aside peripheral wall and the surrounding wall being curved or chamfered.3. A disk cartridge according to claim 1, wherein the almost annularprojection is formed at the periphery of the spindle insertion hole. 4.A disk cartridge according to claim 1, wherein the almost annularprojection is formed at a position outwardly separated from theperiphery of the spindle insertion hole, opposite ends of the annularprojection finishing at a root portion of each triangular projection. 5.A disk cartridge according to claim 3, wherein the almost annularprojection has a slippery property.
 6. A disk cartridge according toclaim 4, wherein the almost annular projection has a slippery property.